Monitoring cardiac and respiratory events is of clinical importance in the early detection of potentially fatal conditions. Current technologies involve contact sensors the individual must wear constantly. Such a requirement can lead to patient discomfort, dependency, loss of dignity, and further may fail due to a variety of reasons including refusal to wear the monitoring device. Elderly patients are even more likely to suffer from the adverse effects of continued monitoring. Unobtrusive, non-contact, imaging based methods are increasingly needed for monitoring patients. One such system uses a single channel camera under structured and unstructured illuminations to capture video of a subject of interest such that the system can monitor both the cardiac and respiratory events. The system isolates pixels associated with the subject's vascular pathways within each frame from the image frames comprising pixels with intensity values corresponding to detected reflected energy projected by unstructured illumination source and estimates subject's chest volume by reconstructing 3D depth map from the image frames comprising pixels corresponding to detected reflected energy projected by structured illumination source. This system requires the simultaneous projection of structured and unstructured light sources. However, artifacts due to the interference caused by the use of structured light patterns have arisen. Such artifacts can adversely impact on the 3D surface reconstruction and vascular pattern detection. For example, FIG. 1 shows an image of a random structured light pattern projected onto a subject's hand. FIG. 2 shows pixels having been classified as corresponding to the projected structured illumination pattern in the image of FIG. 1. Pixels from the projected dot pattern of the structured illumination source can alter the extracted underlying vascular patterns even when interpolated with values of surrounding pixels, especially wherein the blood vessels therein are narrow or short and the projected dot pattern has a relatively high density. This can negatively impact cardiac/respiratory data derived from information associated with pixels of the subject's blood vessels.
Accordingly, what is needed in this art are sophisticated methods for enabling hybrid video capture of a scene being illuminated with structured and unstructured illumination sources.